Desulphurization of gasolines



Patented Ja 2,185,577, p DESULPHURIZATION F oAsoLINEs 1, Alexis Voorhies, Jr., and Eldon E. Stahly, Baton Rouge, La., assignorsyto Standard OilDevclopment Company,{a corporation of Delaware Application December 23, 1936, Serial. No. 117,357

7 Claims. (Cl. 196- -31) The present invention relates to the desul-- phurization of olefinic gasolines, particularly to the type'of gasoline which'is obtained by the polymerization of normally gaseous olefins under vber 8 in which it separates into two layers, the

The separation of the gasoline from the acid maybefacilitated by the addition of water to the extract. This procedure has the disadvantage, however, that it requires either a later conconditions leading to the production of olefins of centration of the acid before the latter can be 5 higher molecular weight. The process-of the employed for" another extraction or a change in present invention is also applicable to olefinic the extraction conditions. gasolines produced/by solvent extraction of In a specific application of the process of the cracked naphthas [predominantly composed of present inven ion aga lin p s d f p lyi0 olefinsandrnaphthas;produced by the catalytic merized butylenes and containing 0.4% of sul-' 10 dehydrogenation of straight run parafiinc naphphur was contacted with lbs ./gal. of 60% sulthas. v v 1 phuric acid at atemperature of- 225 F. The. Accordingto vtheizaresent invention, gasolines gasoline recovered from the sulphuric acid exwhich arejalmost or entirely composed of olefins, tract had a. sulphurcontent of only 0.04%. 15 and containing sulphur compounds, are desul- It is apparent-that 'various changes maybe 15 phurized by being dissolved in hot sulphuric acid I made in the process described above without deof a concentration ranging from" about 45 to 75%. par from the 6 0f e D1 m ve The sulphuric acid'dissolvesthe'olefinhydrocar For example, the extraction operation. may be bonsto the exclusion of the sulphur compounds. conducted in stages in the manner. known in the 2o The operation is conducted, at a temperature I acid treating of gasoline as it is commonly pracabove room temperature but below that at which ticed, or, if desired, the process may be conducted the gasoline begins to vaporize. In general, the as abatch operation. l v g temperature of operation may be stated to be a The process of thepresent. invention may be temperature at'which the olefinic hydrocarbons employed with particular advantage as the first are miscible with sulphuric acid' of the strength step in the'desulphurization of and the improve- 25 designated,v and is usually between 150 F. and ment. of the octane numberof gasoline contain- 250 F. -In some cases; where temperatures near ing sulphur compounds, olefins, paraifins, and/or the upper end of the range are employed, it is naphthenes. It is desirable to subject such gasodesirable to operate under a sufiiciently elevated lines to also-called reforming-treatment, preferpressure to prevent vaporization-of the gasoline. ably at a temperature ranging from about 800 F. 30

The process of the, present invention may be to 1100 -F. in the presence of a catalyst which better understood from the following description may be ether a straight dehydrogenation catalyst of the accompanying drawing in-which is illus, or one which functions both as a dehydrogena- 'trated in diagrammatie'form a front elevation of tion and a desulphurization catalyst. Bauxite,

- anapparatus suitable for carrying out saidprocferrous sulphide, calcium sulphide, and the 0x- 35 ess. Referring to the drawing specifically, [is a ides and'sulphides'of metals of group VI, of the contact tower-which is preferably filled with periodic system, preferably in conjunction with lumps of inert materialsuch as stoneware, porcealumina, may be mentioned as typical examples lain, or carbon Raschig rings, and which is pro: of suitable catalysts. I v

40 vided witha gasoline feed line 2, an acid feed line Such catalytic treatments proceed, more 40 3, a rafiinate (which contains the sulphur ,comsmoothly when the feedstock is free from olepounds) outlet 4, and an extract .(containing the fins. By applyingthe'sulphuric acid extraction purified gasoline) outlet 6. of the present invention to such a mixed feed it The operation illustrated is'a continuous opis possible. to obtain a. substantially sulphur-free eration in which the gasoline to be purified is olefin extract anda substantially olefin-free sul- 45 v 7 passed countercurrent to the'acid employed. The phur-containing rafflnate as a feed stock for the I extract is conducted thru line 6 and thru a coolcatalytic'treatment. The reaction product from ling coil 1 in which it is cooled to a point below the catalytic treatment may be furtherfextracted' the miscibility temperature of .the gasoline and with sulphuric acid and the rafflnate of this secthe sulphuric acid, and then to a settling chamond extraction recycled to the catalytic treatment 50 or said product may be blended with the olefinic extract obtained in the first extraction. H

The nature and objects of thepresent'invention having been thus'clescribed and illustrated by a practical embodiment thereof, what is claimed, as new and useful and desired to be 4. A processaccording toclaim 1 in whichsaid secured by Letters Patent is:

l. A process for desulphurizing sulphur con taining gasoline composed predominantly of olefinic polymers which comprises intimately mixing said gasoline with sulphuric acid of between about and about concentration and at a temperature suificient to render a substantialpart of said acid miscible with said polymers, separating the resulting mixture into a hydrocarbon layer containing more sulphur than said gasoline. originallycontained and a sulphuric acid layer containing hydrocarbon polymers and less of the sulphur compounds than said polymers originally contained, and recovering from said sulphuric acid layer a hydrocarbon mixture boiling within the gasoline range and hav'inga reduced sulphur content. a I

2. A process as in claim 1 inwhich the hydrocarbon mixture boiling Within the gasoline range and having a, reduced sulphur content is recovered from the sulphuric acid layer by cooling the sulphuric acid layer to a temperature at which the olefins and the sulphuric acid are substantially immiscible.

3. A process for'the desulphurizationof sulphur-containing olefinic' polymers boiling within the gasoline range which comprises intimately mixing said polymers withsulphuric acid of a strength ranging from about45 to about 75% and at a temperature at which the hydrocarbon constituents of the polymer aresubstantially miscible with said sulphuric acid thereby forming a sulphuric'acid extract containing olefinic polymer hydrocarbons and substantially less of the sulphur compounds than said hydrocarbons originally contained, separating said extract from un- 1 dissolved high sulphur-containing hydrocarbon constituents, cooling said extract to a tempera ture at which the hydrocarbon polymers are substantially immiscible with the sulphuric acid and recovering desulphurized polymers boiling within the gasoline range by separating the hydro carbon layer from the sulphuric acid layer.

sulphur-containing gasoline is'composed of poly-,* I

merized butylenes, said polymers beingobtainedby means of the'actio'n of sulphuric acid'on;

butylenes under polymerizing conditions;

5. A process for producing a substantially sul phur-free olefinic polymer gasoline from a gasoline comprising essentially olefinic, polymers but containing a small amountof sulphur compounds which comprises intimately mixing said gasoline with sulphuric acid of a strength vranging from" 7 about 45% to about 75% at a temperature from about F. to about 250 F., separating the undissolved hydrocarbons and sulphuricompounds from the sulphuric acid extract, recovering the "dissolvedolefinic polymer gasoline substantially free of sulphur compounds from the sulphuric acid extract by cooling said extract to a temperature atwhi'ch the olefinic polymer gasoline is substan-* tially immiscible with the sulphuric acid' andremoving the hydrocarbon layer from the sulphuric acid layer.

' 6' A process of e h ne'afi xture 0f hydrocarbons boiling within the gasoline ra l 25 containing sulphur and composedchiefiy of polymer'lzed normally gaseous mono-olefins which comprises intimately mixing with said, mixture sulphuric acid of a concentration between about 45 and about 75% at a temperature- ,offlbetwe'en about 150 and about 250 1a, separating the not sor acid layerfrom the hydrocarbonilayer, allowing the acid layer mixture to cool below the mischbilitytemperature of the sulphuric acid andpolyf meric gasoline, and separating the purified olefinic polymer boiling within the gasoline boiling'range o from the acid ii if 3' 7. A process 'as in claim 1 1 wherein the sulline countercurre-ntly.

;' ELDOiN E. s'rAHnY.

' phuric acid separated from-the purified olefinic polymer hydrocarbonmixture is reheated to the treating temperature and recycled and'contacted with fresh sulphur-containing polymeric gaso-- 

